The present invention relates to isolated multi-channel LED drivers. More particularly, the present invention relates to an LED driver configuration providing protection against output short circuits, and/or against abnormal output connections.
Light emitting diode (LED) lighting is growing in popularity due to decreasing costs and long life compared to incandescent lighting and fluorescent lighting. LED lighting can also be dimmed without impairing the useful life of the LED light source.
A particular CLASS-2 LED driver for multi-channel LED configurations is defined in Underwriters Laboratories specifications. Such a configuration is desirable because of its smaller size, low fixture design cost and easier and better thermal management on the fixture design side. However, the U.L. specification requires the multi-channel LED driver to be isolated and have a maximum output voltage of less than 60 volts DC at any given time.
The multi-channel LED driver must also be able to pass a short circuit test, or in other words be sufficiently protected against short circuit conditions. In addition, the multi-channel driver must be configured to survive output abnormal connections (i.e., in parallel or series connection). If a light source such as an LED module containing an array of lighting elements is coupled on a first end to a terminal in a first channel, and on a second end to a terminal in a second channel, the driver must be designed to survive such a condition.